A Milwaukee Democrat's primary challenge to a longtime state senator has set up a quintessential showdown between an eager up-and-comer and an experienced incumbent, with education and gun control emerging as critical issues.

Rep. Mandela Barnes (D-Milwaukee) announced in April that he would vacate his Assembly seat to run against Sen. Lena Taylor (D-Milwaukee), promising "fresh, transformational" leadership. Taylor countered she was the better fit, citing her experience fighting "unrelentingly" for her constituents.

Taylor was elected to the 4th Senate District in 2004 and has never before faced a primary challenge. During much of her tenure, Taylor has served on the budget-writing Joint Finance Committee, giving her a chance to help secure funding for her district.

Barnes was elected to the Assembly in 2012 and was the chairman of the Legislature's black and Latino caucus. In his first two races, he ran on a platform centered on reforming public education. This race puts Barnes in an up-or-out position — elected officials in Wisconsin cannot run for two state offices simultaneously.

Both Taylor and Barnes are well-regarded in the overwhelmingly Democratic district, which covers parts of Milwaukee's north side, Glendale, Shorewood and a sliver of Wauwatosa. To some, the race is viewed as a referendum on progressive values within the African-American community.

The race may come down to voters in Shorewood, who are disproportionately electorally active. In the August 2014 primary, 34% of registered Shorewood voters turned out — a number that's considered high in an election that typically sees low voter turnout.

The Milwaukee Democrats have each seen strong support from Shorewood voters in the past. Mordecai Lee, a political-science professor at the University of Wisconsin-Milwaukee and former state senator, said that he was hard-pressed to determine which candidate voters would throw their support behind.

"This is the archetypal race between incumbent and challenger. It's attracting a lot of attention and justifiably so," Lee said. "(The seat) is not widely thought of as being weak or vulnerable to a challenge. It remains to be seen who has a better sense of that district."

"It'll come down to intangibles, who is better at doors, who is better at organizing, who has the relationships," Lee said. "It's not an ideological showdown."

But there are two key areas where the candidates diverge — education and gun control.

Taylor supported GOP Gov. Scott Walker's plan to increase the per-pupil aid to voucher and charter schools. She has been a longtime supporter of alternatives to public education, but is quick to point out the role she played in passing a series of reforms in the 2009 state budget to the Milwaukee Parental Choice Program, including requiring voucher schools to give their students some of the same evaluations as public schools. She has also criticized a program created by Walker and Republican lawmakers last year that allows an appointed commissioner to take control of underperforming public schools in Milwaukee.

While Barnes has also been a vocal critic of that plan, he has gone further than Taylor in faulting the move toward voucher schools. He instead advocates for the implementation of a community schools model that encourages partnership programs to provide children with wraparound services — academic, health and social services — to transform underperforming schools.

Last year, with state Sen. Chris Larson (D-Milwaukee), Barnes introduced legislation that would have provided start-up funding for the creation of more community schools. As with most Democratic proposals, it made little progress in the Republican-controlled Legislature.

In an interview, Taylor said she didn't disagree with the community school model, but thought that "we need to do something larger than that," pointing to providing schools with career-based partnerships.

Barnes has sought to bring the issue of gun control out front and center, taking to Twitter after the mass shooting at a gay nightclub in Orlando, Fla., to condemn the nation's "love affair with guns."

By contrast, Taylor once described guns as "pieces of art" and voted for bills allowing people to carry concealed weapons and establishing the castle doctrine, which provides legal protections to people who shoot home intruders. Though Taylor acknowledged that neither of the bills was perfect in her view, she said concealed carry was already a reality for many of the constituents in her district and she thought the concealed carry law ultimately struck a correct balance between public safety and Second Amendment rights.

In voting for that bill, Taylor introduced an amendment that would have required increased hours of training and smaller class sizes for individuals with concealed carry. It failed to pass. She is quick to add that she has also advocated for a series of "common sense measures" to restrict access to guns, including forcing domestic abusers to surrender their guns and opposing measures to repeal a 48-hour waiting period for handgun purchases.

Barnes, on the other hand, has sharply criticized the concealed carry and castle doctrine laws as being contrary to public safety. Castle doctrine, he said, "should not be a license to kill."

In Barnes' most recent finance report, his campaign in January had nearly four times as much cash on hand as Taylor's campaign — approximately $41,000, compared to Taylor's $11,000. Taylor's report shows she has lent herself nearly $54,000.

The primary is Aug. 9. The winner is all but certain of taking the seat because no Republican is running.